Dennis Quaid: 'Happy Ending' After Twins' Medical Scare

The joys of being a new dad are especially sweet for Dennis Quaid, whose four-month-old twins survived a near-fatal drug overdose while hospitalized late last year.

"It's the greatest thing to hold those kids and see their faces because we had a happy ending," he told PEOPLE. "It's great be a normal dad with the normal problems of not having enough hands for both of them."

The 53-year-old actor and his wife Kimberly, 36, welcomed twins Thomas Boone and Zoe Grace on Nov. 8. (The babies were born via gestational carrier). But later that month, the two were accidentally given a massive overdose of the blood thinner Heparin while hospitalized at L.A.'s Cedars-Sinai Medical Center – and spent days battling for their lives.

"I do have a greater appreciation of life in general," said Quaid, who spoke about his harrowing ordeal and the widespread problem of medical errors at the opening session of the Association of Health Care Journalists's annual conference in Washington, D.C. on Thursday. "If they hadn't made it, it really would have changed my life. But they did survive. So it changed my attitude."

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State regulators fined Cedars-Sinai $25,000 last week for giving the overdoses to the Quaid twins and another newborn.

The Quaids – who are launching a foundation aimed at reducing the number of medical mistakes – have also filed a lawsuit against Heparin's drug maker, Baxter Healthcare Corp., accusing it of negligence in packaging adult and pediatric doses in similar vials.

Human error in hospitals "is one of the leading causes of death in our country, [greater] than automobile accidents, breast cancer or AIDS," Quaid – accompanied by his 15-year-old son Jack, whose mom is Meg Ryan – told the audience.

"Yet because they happen one case at a time, they tend to slip under the public radar unless you're a celebrity," he explained. "Because it happened to my family, it was all over the national news. I realized we have an opportunity to raise public awareness about this."

So how are Zoe and Boone doing now? "Fantastic," he said. Adding jokingly, “Their progress and their development appears to be completely normal – aside from being a Quaid."